Fellow Grand Prix'ers:
I need some help troubleshooting the source of this noise. I have a 2006 baseline Grand Prix, 3.8L (VIN 2), 90,000 miles. Here are my symptoms and troubleshooting steps to date:
-When I accelerate normally, I hear 4-6 distinct creaking/squeaking/popping sounds as the drive train loads up with torque. When I let off the gas, it creaks/squeaks/pops the same number of times as the torque is unloaded. It is extremely annoying to hear this during every acceleration. If I accelerate and decelerate gently, I can reach highway speed without generating the sound but it annoys the people behind me.
-I have a moderate torque steer to the right during acceleration, enough to change lanes and drive off the shoulder if I were to let go of the steering wheel
-I originally thought it was a suspension problem. Me and my friend bounced the car in every possible direction without being able to duplicate the noise. I replaced all 4 struts AND strut mounts because I was told that they were weak during my State Inspection, and it improved my ride but did nothing to help the noise. I kept the same OEM springs though.
-I do not believe it is a suspension problem now... When I put the car in Drive with the parking brake set and my left foot on the brake, I can duplicate the noise with a quick rev of the accelerator even though the car is not in motion and there is no body movement. It seems to be coming from the front right side, according to outside observers. If I rev the throttle with the car in Park or Neutral, the noise is not there. The noise only appears under a drive train torque load.
At this point, I think it might be the lower right motor mount, but upon initial inspection the mount appears to be in good shape. I do not see any deteriorating rubber or any other obvious signs of it being bad. I disconnected my torque struts and rocked the engine on its two lower mounts and was not able to duplicate the noise.
Do you guys agree that it is the lower right motor mount, or is there any chance it could be:
-Exhaust pipe mating noise?
-Internal transmission noise?
-CV Joint noise?
-Something else?
Replacing the motor mount is going to be a huge undertaking for me since I will have to procure an engine hoist, but that's where I'm at unless someone can point me in another direction. I'm a pretty skilled DIY mechanic but cannot afford the time or money to get this one wrong. I'm hoping that somebody on this forum has dealt with this issue!
Thank you,
Denny Smith
